q_maxUpwards and q_maxDownwards cause issues for units with multiple endogenous inputs (and probably outputs).
unit is defined with multiple different inputs, an online variable and a minimum load, the
q_maxDownwards constraints are generated for both of the input
gnu as well, enforcing a minimum consumption for the inputs separately.
While this is sometimes desired, the current implementation prevents creating
units with minimum loads that can choose between two different input
nodes (or a mix from both). Similarly,
units with multiple outputs and a minimum load cannot currently be made to freely choose their output ratio.